Forest and agricultural land‐use‐dependent CO₂ exchange in Thuringia, Germany

Abstract

Eddy covariance was used to measure the net CO 2 exchange (NEE) over ecosystems differing in land use (forest and agriculture) in Thuringia, Germany. Measurements were carried out at a managed, even-aged European beech stand (Fagus sylvatica, 70-150 years old), an unmanaged, uneven-aged mixed beech stand in a late stage of development (F. sylvatica, Fraxinus excelsior, Acer pseudoplantanus, and other hardwood trees, 0-250 years old), a managed young Norway spruce stand (Picea abies, 50 years old), and an agricultural field growing winter wheat in 2001, and potato in 2002. Large contrasts were found in NEE rates between the land uses of the ecosystems. The managed and unmanaged beech sites had very similar net CO 2 uptake rates ($À480 to À500 g C m À2 yr À1 ). Main differences in seasonal NEE patterns between the beech sites were because of a later leaf emergence and higher maximum leaf area index at the unmanaged beech site, probably as a result of the species mix at the site. In contrast, the spruce stand had a higher CO 2 uptake in spring but substantially lower net CO 2 uptake in summer than the beech stands. This resulted in a near neutral annual NEE (À4 g C m À2 yr À1 ), mainly attributable to an ecosystem respiration rate almost twice as high as that of the beech stands, despite slightly lower temperatures, because of the higher elevation. Crops in the agricultural field had high CO 2 uptake rates, but growing season length was short compared with the forest ecosystems. Therefore, the agricultural land had low-to-moderate annual net CO 2 uptake (À34 to À193 g C m À2 ), but with annual harvest taken into account it will be a source of CO 2 ( 1 97 to 1 386 g C m À2 ). The annually changing patchwork of crops will have strong consequences on the regions' seasonal and annual carbon exchange. Thus, not only land use, but also land-use history and site-specific management decisions affect the large-scale carbon balance.

Carbon budgets for an irrigated intensively grazed dairy pasture and an unirrigated winter-grazed pasture

“…Similar behaviour has been observed elsewhere, for forests as well as agricultural sites. For example, Anthoni et al (2004) reported that the uncertainties in annual NEE for ±0.1 m s −1 variation of the u * threshold ranged from 9 to 62 g C m −2 yr −1 across four sites in different ecosystems. The threshold-dependent variations of NEP at the IFR and UUW sites are of same sign and comparable magnitude as those of Anthoni et al (2004).…”

“…For example, Anthoni et al (2004) reported that the uncertainties in annual NEE for ±0.1 m s −1 variation of the u * threshold ranged from 9 to 62 g C m −2 yr −1 across four sites in different ecosystems. The threshold-dependent variations of NEP at the IFR and UUW sites are of same sign and comparable magnitude as those of Anthoni et al (2004). Both GPP and ER increased with increasing data-gap fraction but the latter variable showed the stronger dependence in line with NEP decreasing with increasing data-gap fraction.…”

Influence of wood density in tree-ring-based annual productivity assessments and its errors in Norway spruce

“…), which was amply used for eddy covariance measurements (e.g. Anthoni et al, 2004) or biomass modelling (Wirth et al, 2004). The site is characterized by mono-specific Norway spruce (Picea abies L.) stands.…”

Quantifying the relative importance of greenhouse gas emissions from current and future savanna land use change across northern Australia

“…These studies typically compare microclimate and fluxes of GHGs from pastures and/or crops with adjacent for-est ecosystems under a range of management conditions (e.g. Anthoni et al, 2004;Zona et al, 2013) or natural grasslands and different cropping types (e.g. Zenone et al, 2011).…”